Rf transmit architecture methods

ABSTRACT

A transmitter device is switchably operable in a digital IQ mode (DIQM) of operation and a polar mode (PM) of operation. The device has a switch logic processor that determines an attribute of operation of the transmitter device. When a first condition of the attribute is met, the switch is to switch to or remain in the PM, and when a second condition of the attribute is met, the switch is to switch to or remain in the DIQM. The attribute may be: a modulation bandwidth to be used during a transmission time slot, whether a transmission is to be a non-contiguous single-carrier transmission or a non-contiguous multiple-carrier transmission, a contiguous single-carrier transmission or a contiguous multiple-carrier transmission, whether a low or high EVM mode transmission is to be used during a transmission time period, whether an LTE, a 5G, or a Wi-Fi mode transmission is to be used, among others.

TECHNICAL FIELD

The present disclosure relates to methods for operating a radiofrequency digital to analog converter that is capable of operating ineither a polar mode or a digital IQ mode.

BACKGROUND

U.S. Pat. No. 8,891,681 (the '681 Patent) describes a transmittercapable of switching between operation in a first mode which provides avector-modulated RF output signal (also called digital IQ mode (DIQM)),and a second mode which provides a polar-modulated RF output signal(also called polar mode (PM)).

The polar transmit architecture offers a lower power consumptioncompared to IQ architectures, while high modulation bandwidths areeasier achieved with IQ transmit architectures. However, it may bedifficult to utilize a switchable architecture in order to achieve agood power consumption vs. design complexity tradeoff.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 & 2 are block diagrams that replicate FIG. 1A and FIG. 1B of the'681 Patent;

FIGS. 3 and 4 are pictorial schematic diagrams that replicate FIGS. 2Cand 2F of the '681 Patent;

FIG. 5 is a block diagram the combines similar FIGS. 1 and 2, andexpressly shows a transmitter with a switch as well as switch logic,according to various implementations as described herein;

FIG. 6 is a flowchart that illustrates a process for the variousswitching determinations and switch logic, according to variousimplementations described herein; and

FIG. 7 is a block diagram illustrating a machine that may be a computeron which various processes described herein may be performed, inaccordance with some aspects of the inventive subject matter.

DETAILED DESCRIPTION

The following is a detailed description of various configurationsdepicted in the accompanying drawings. However, the amount of detailoffered is not intended to limit anticipated variations of the describedconfigurations; to the contrary, the claims and detailed description areto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the present teachings as defined by the claims.The detailed descriptions below are designed to make such configurationsunderstandable to a person having ordinary skill in the art.

The basic architecture of the '681 Patent is described to provide a basefor the novel features described herein.

FIGS. 1 and 2 are block diagrams that essentially replicate FIG. 1A andFIG. 1B of the '681 Patent.

FIG. 1 shows the transmitter 100 in a first mode, in which thetransmitter is designed to provide a vector-modulated RF output signal,and FIG. 2 shows the transmitter 100 in a second mode, in which thetransmitter is designed to provide a polar-modulated RF output signalwhich may be generated by modulation of an oscillator or by modulating adigital to time controller (DTC).

The transmitter 100 comprises a baseband signal path 101, a frequencysynthesizer 103 and a radio-frequency digital-to-analogue converter(RF-DAC) 105.

The baseband signal path 101 is designed to provide a first basebandsignal 107 having an in-phase component 107A and a quadrature component107B in the first mode of the transmitter 100. The frequency synthesizer103 is designed to provide an oscillator signal 109. Furthermore, thefrequency synthesizer 103 is designed to provide the oscillator signal109 as an unmodulated signal in the first mode of the transmitter 100.The RF-DAC 105 is designed to receive the first baseband signal 107 andthe oscillator signal 109, and is furthermore designed to provide, inthe first mode, a vector-modulated RF output signal 111, on the basis ofthe first baseband signal 107 and the oscillator signal 109 (as anunmodulated signal).

Furthermore (as is shown in FIG. 2), the baseband signal path 101 isdesigned to provide a second baseband signal 113 having an amplitudecomponent 113A and a phase component 113B in the second mode of thetransmitter 100. The oscillator 103 is furthermore designed to providethe oscillator signal 109 as a modulated signal in the second mode ofthe transmitter 100. A modulation of the oscillator signal 109 in thesecond mode is based on the phase component 113B of the second basebandsignal 113 (provided by the baseband signal path 101).

The RF-DAC 105 is furthermore designed to receive the amplitudecomponent 113A of the second baseband signal 113, and is furthermoredesigned to provide, in the second mode of the transmitter 100, apolar-modulated RF output signal 115, on the basis of the amplitudecomponent 113A of the second baseband signal 113 and of the oscillatorsignal 109 (a modulation thereof is based on the phase component 113B ofthe second baseband signal 113).

The transmitter 100 may be designed to switch from the first mode, shownin FIG. 1, into the second mode, shown in FIG. 2, or from the secondmode into the first mode.

Consequently, the transmitter 100 shown in FIGS. 1 and 2 is designed toperform a vector modulation (also called IQ modulation) in the firstmode and a polar modulation in the second mode. Thus it is possible toprovide a configurable TX (transmit) architecture with both polarmodulation and IQ modulation.

Furthermore, as may be seen from FIGS. 1 and 2, one and the same RF-DAC105 and also one and the same frequency synthesizer 103 may be used forthe vector modulation (in the first mode) and the polar modulation (inthe second mode), although this configuration is not essential to thesystems and methods described herein.

As an example, for a modulation bandwidth to a given, predeterminedbandwidth threshold (e.g., 5 MHz, 20 MHz, or 50 MHz), the transmitter100 (and therefore also the RF-DAC 105) may operate as a polar modulator(in the second mode) and, for a modulation width above the predeterminedbandwidth threshold (e.g., for the case of Long Term Evolution (LTE)carrier aggregation), the transmitter 100 (and therefore also the RF-DAC105) may operate as an IQ or vector modulator (in the first mode).Therefore, the baseband signal path 101 is also configurable betweenthese two modes. As an example, the baseband signal path 101 may have aCOordinate Rotation Digital Computer (CORDIC) module, which may be usedonly in the second mode, while it is bypassed in the first mode. Oneadvantage is a lower current consumption for the 2G/3G and 4G standardspredominantly in use, as a result of using a polar modulation (in thesecond mode).

A further advantage of this example is that the problems which occur inparticular for polar modulation systems having a high bandwidth, thatthe modulation of the DCO and the delay between the amplitude componentand the phase component become critical, may be prevented by switchinginto the vector modulation mode for these high bandwidths. Consequently,these problems no longer occur since, in the vector modulation mode, theoscillator signal 109 is to be provided as an unmodulated signal.

As a further example, for a single-antenna transmission mode, thetransmitter 100 may operate in the second mode (as a polar modulator),and the phase-modulated oscillator signal 109 is to be provided by thefrequency synthesizer 103, e.g., with a phase-modulated DCO (digitallycontrolled oscillator). For a multi-antenna transmission mode, thetransmitter 100 may be operated in the first mode (as a vectormodulator), in which the unmodulated oscillator signal 109 is providedby the frequency synthesizer 103. One advantage of this example is anexpected lower current consumption for the multi-antenna transmissionmode (e.g., multiple input multiple output (MIMO)) as a result of usingthe IQ or vector modulation mode, while a low current consumption in thesingle-transmission mode predominantly in use is furthermore maintainedusing the polar modulation mode (the second mode).

In contrast to this, conventional systems using only a polar modulationwould require a plurality of synthesizers for generating the differenttransmission signals, which usually leads to a higher currentconsumption for the polar modulator concept in comparison with thevector modulator concept.

The baseband signal path 101 may be designed to receive (digital) datasignals 117, and may be designed to provide the first baseband signal107 in the first mode and the second baseband signal 113 in the secondmode on the basis of the data signals 117. Consequently, the datasignals 117 may be independent of the current mode of the transmitter100, and the baseband signal path 101 may supply the first basebandsignal 107 having the in-phase component 107A and the quadraturecomponent 107B if the transmitter 100 is presently in the first mode, ormay supply the second baseband signal 113 having the amplitude component113A and the phase component 113B if the transmitter 100 is at presentin the second mode.

As discussed above, the mode of the transmitter 100 may be selected(e.g., by the transmitter itself) depending on a resulting modulationbandwidth (of the resulting RF output signal 111, 115) and/or the numberof RF output signals which are intended to be provided simultaneously(e.g., single-antenna mode or multi-antenna mode).

A frequency of the oscillator signal 109 in the first mode and thesecond mode may be selected depending on the communication standardwhich is required for the RF output signals, and may be, for example, acarrier frequency of such a communication standard.

In the case of the vector modulation mode or first mode of thetransmitter 100, the oscillator signal 109 is provided as an unmodulatedsignal, for example having a fixed RF-LO (local oscillator) frequency.In the case of the polar modulator mode or the second mode of thetransmitter 100, the oscillator signal 109 is provided as a modulatedsignal, for example as a phase-modulated LO signal (the carrierfrequency mentioned being superposed with the phase modulation,determined by the phase component 13B of the second baseband signal113).

As an example, the RF-DAC 105 may have 256 of these in-phase mixer cells101A and 256 of these quadrature mixer cells 203A in order to achieve512 I-paths and 512 Q-paths.

FIGS. 3 and 4 are pictorial schematic diagrams that replicate FIGS. 2Cand 2F of the '681 Patent.

FIG. 3 is pictorial schematic diagram of a circuit of a known RF-DAC 105having 256 in-phase mixer cells 201A, 201B and 256 quadrature mixercells 203A, 203B. The quadrature mixer cell 203A is correspondinglycoupled to the common summing terminal 207 in order to achieve thedesired mixing of the in-phase component 107A and the quadraturecomponent 107B of the first baseband signal 107, in order to obtain thevector-modulated RF output signal 111 as a result of this mixing.

Furthermore, as is shown in FIG. 3, the different differentialoscillator signals (the in-phase oscillator signal 209A and thequadrature oscillator signal 209B) may already be provided by thefrequency synthesizer 103 and are distributed in the RF-DAC 105 amongtheir assigned in-phase mixer cells 201A, 201B or quadrature mixer cells203A, 203B.

Furthermore, as may be seen from FIG. 3, the RF-DAC 105 may have a firstrow decoder and a first column decoder for the in-phase mixer cells201A, 201B and a second row decoder and a second column decoder for thequadrature mixer cells 203A, 203B.

The first row decoder and the first column decoder may be designed todetermine a plurality of vector modulation control signals for thein-phase mixer cells 201 a, 201B on the basis of the in-phase component107A. The second row decoder and the second column decoder may bedesigned to determine a plurality of vector modulation control signalsfor the quadrature mixer cells 203A, 203B on the basis of the quadraturecomponent 107B.

To put it another way, FIG. 3 shows a digital vector modulator havingdistributed mixers (the mixer cells 201A, 201B and the mixer cells 203A,203B) in which the mixing of the carrier signal (of the oscillatorsignal 109) with the digital baseband signal (the first baseband signal107) is effected in the digital control circuit (realized by the mixercells 201A. 201B and 203A, 203B). As an example, the in-phase component107A and the quadrature component 107B may in each case correspond to abinary output word in response to which the decoder 205 activates ordeactivates specific mixer cells and therefore activates or deactivatesspecific controllable current sources of the mixer cells 201A, 201B,203A, 203B. The digital-to-analogue conversion and the radio-frequencymixing are effected in each individual mixer cell (or element) of thetwo cell arrays, shown in FIG. 3.

As was mentioned in conjunction with FIG. 1, the RF-DAC 105 is designedto provide, in the second mode of the transmitter 100, thepolar-modulated RF output signal 115 on the basis of the oscillatorsignal 109 (which is a modulated signal) and the amplitude component113A of the second baseband signal 113. Consequently, differentpossibilities of the implementation of the RF-DAC 105 for the secondmode of the transmitter 100 are described below, in which bothimplementations have the same features insofar as at least some of themixer cells of the RF-DAC 105 are used in the first mode for providingthe vector-modulated RF output signal 111 and are also used in thesecond mode for providing the polar-modulated RF output signal 115.

In a first example, for an implementation of the RF-DAC 105, only aportion of the mixer cells of the RF-DAC 105 which are used forproviding the vector-modulated RF output signal 111 in the first modeare used for providing the polar-modulated RF output signal 115 in thesecond mode.

In the example described below, the in-phase mixer cells (e.g., thein-phase mixer cells 201A, 201B) of the RF-DAC 105 are used forproviding the polar-modulated RF output signal 115. Instead of using thein-phase mixer cells, it is also possible to use the quadrature mixercells (e.g., the quadrature mixer cells 203A, 203B) for providing thepolar-modulated RF output signal 115. It is also possible to use only aportion of the in-phase mixer cells or quadrature mixer cells forproviding the polar-modulated RF output signal 115.

In the configuration in which the same RF-DAC 105 is used for providingthe vector-modulated RF output signal 111 in the first mode and thepolar-modulated RF output signal 115 in the second mode, the structureremains the same (e.g., the mutual connection between the mixer cells ofthe RF-DAC 105). Usually, the only difference between the first mode andthe second mode in the RF-DAC 105 is the function of the decoder 205,which supplies the control signals and the oscillator signals to aplurality of mixer cells 201A, 201B, 203A, 203B.

FIG. 4 is a pictorial schematic diagram that shows the implementation ofthe RF-DAC 105 from FIG. 3 in the second mode using the implementationin which only the first sub-plurality 201 of the mixer cells 201A, 201Bis used for providing the polar-modulated RF output signal 115. As isshown in FIG. 4, it suffices to provide the oscillator signal 109 andthe amplitude component 113A of the second baseband signal 113 for thefirst row decoder and for the first column decoder of the decoder 205for the in-phase mixer cells 201A, 201B. Furthermore, as may be seenfrom FIG. 4, the frequency synthesizer 103 is designed, in the secondmode, to receive the phase component 113B of the second baseband signal113 and to provide the oscillator signal 109 as a modulated signal onthe basis of the phase component 113B. The first row decoder and thefirst column decoder are designed to provide, on the basis of theamplitude component 113 a, the polar modulation control signals 241A,241B for the mixer cells 201A, 201B for activating, depending on theamplitude component 113A, specific mixer cells of the firstsub-plurality 201 of the mixer cells 201A, 201B.

A superposition of the output signals of the activated mixer cells atthe common summing terminal 207 is the polar-modulated RF output signal115 for example as a differential signal.

The RF-DAC 205 may be designed to use the first sub-plurality 201 ofmixer cells 201A, 201B and the second sub-plurality 203 of mixer cells203A, 203B in the second mode for providing the polar-modulated RFoutput signal 115.

Despite the known structures describe above, however, precise criteriaand methods for utilizing this structure have not been provided. Thus,the following describes methods for using the RDFAC in PM or DIQM thatis dependent on the requirements of the RF system. These criteria andmethods may include: 1) low-bandwidth to high-bandwidth transitions; 2)non-contiguous single carrier to multiple carrier transitions; 3)contiguous single carrier to dual carrier-multiple carrier transitions;4) low error vector magnitude (EVM) to high EVM transitions; 5) LTE to5G transitions; and 6) LTE to Wi-Fi transitions. Benefits of use mayinclude power efficiency, optimizing use of available signal bandwidth,oscillator mapping, or oscillator count (for example, chip size)optimization.

FIG. 5 is a block diagram the combines similar FIGS. 1 and 2, andexpressly shows a transmitter 100 with a switch 120 that allows theswitching from the first mode (DIQM) to the second mode (PM), although,as noted above, the design is not limited herein to a single RF-DACdesign. Connected to the switch 120 is the newly defined switch logic130 that, based on a control input 118, provides to the switch 120whether or not to change state based on various criteria. The switchlogic may be implemented in hardware, software, or any combination ofthe two.

The following use case is considered below. An LTE voice call uses atransmit bandwidth of 5 MHz followed by a base station request to switchto a 60 MHz signal bandwidth LTE 3×20 MHz In a known architecture of apolar-only mode, the polar TX mode has the best-known power efficiency.However, the drawback is a high tuning range requirement on thedigitally controlled oscillator (DCO). For up to 20 MHz bandwidths, thisrequirement may be achieved with medium effort. However, a DCO designedfor a signal bandwidth of 60 MHz is expected to have a very largevaractor field with a low Q in the tank and a very low band selectiontuning range. This would result in a large chip area and high powerconsumption.

In a known architecture for operating in a DIQM, the IQ TX mode has thebest known TX architecture for high signal bandwidth and low EVMrequirements. The drawback is a large required cellfield per unit ofoutput power, resulting in a higher current consumption. Therefore, theinitial battery current during the LTE voice call is 20-40% higher whenusing the DIQM compared to the PM. Since power consumption during thevoice call is an important key performance indicator (KPI) for the enduser, this results in a competitive disadvantage. When switching to a 60MHz LTE bandwidth, this implementation does not require a change in theDCO tuning range, and it therefore offers a lower chip area (low DCOcount).

In the architecture described herein, switching from the PM to the DIQMmode for transmission combines the advantages of each mode by startingthe LTE voice call in the PM and switching to the DIQM when a largesignal bandwidth is required. The result is an improved powerconsumption and a low chip size overhead for enabling the LTE 60 MHzfeature.

The methods described herein may be utilized by a device having thestructure described above and in the '681 Patent. However, these methodsare not limited to a single RF-DAC that may be operated in DIQM or PM,and thus the device may also include a more general system havingmultiple RF-DACs that may be either operated in DIQM, PM, or a combinedDIQ+polar combination mode. Therefore, the term “device” as used hereinmay include a single or multiple RF-DAC design, and the “switching” of adevice from one mode or the other could employ the single or multipleRF-DACs discussed above.

In one implementation, the base station indicates to a remote unit thatit should change its communication state in some way, for example, thatit should operate in a lower or higher bandwidth mode. When the remoteunit receives that indication, then the device of the remote unit maydetermine that it should switch from the DIQM to the PM, or vice versa,for the next transmission period. The switching from single carrier todual carrier may be fully synchronized between the base station and theremote unit

In one implementation, when the device switches a mode of transmission,that mode of transmission is frozen for some predefined period of time(such as a transmission block) and the device does not switchtransmission modes during a normal transmit operation. The base stationinforms the remote device of the remote device's needed bandwidth sothat the remote device may set its mode properly for the next transmitcycle.

FIG. 6 is a flowchart that illustrates a process 600 for the variousswitching determinations and switch logic 130. The switch logic 130 mayreceive an indication of some form of communication transition S610.Based on the configuration of the switch logic 130, one or more of thelogical decisions S620 may be invoked. The outcome of each of thelogical decisions S620 may be either to operate the transmitter in thePM S670 or operate the transmitter in the DIQM S680.

The logic S620 for the respective decisions is discussed in thefollowing.

1) Low-Modulation Bandwidth to High-Modulation Bandwidth TransitionsS630

When the remote unit receives an indication from the base station toincrease its bandwidth during a particular time period that exceeds somethreshold amount S630:HIGH, the device of the remote unit, if it isoperating in a PM, is switched operate in a DIQM S680. Although thepower consumption is better when operating the device in PM at a lowsignal bandwidth (such as LTE 5), operation in PM is not possible abovesome threshold limit. For example, at present, PM operations aboveapproximately 40 MHz (e.g., LTE 40) are not advantageous since a largetuning bandwidth would lead to a large modulation tuning varactor array,thereby reducing the overall tuning range of each oscillator andresulting in a high oscillator count for a given amount of frequencybands to be supported. Thus, in a present system, the threshold may beset at 40 MHz. This switching threshold may be increased as futuredevelopments permit PM operation at higher bandwidths. Conversely, whenthe remote unit receives an indication from the base station to decreaseits bandwidth that falls below the threshold amount S630:LOW, the deviceof the remote unit, if it is operating in a DIQM, is switched operate ina PM S670.

2) Non-Contiguous Single-Carrier to Dual-Carrier or Multiple-CarrierTransitions S635

When the remote unit receives an indication from the base station thatit is to switch from a single-carrier mode to a non-contiguous dual- (ormultiple-) carrier mode S635:MULTIPLE, the device may be switched fromthe PM to the DIQM S680, and vice versa (S635:SINGLE, S670), and thedecision to switch may be done independent of the bandwidth. This mayalso include performing a switching from PM to DIQM if there is anexpected harmonic crosstalk (due to a change in the DCO frequency).Conversely, it may include a switching from DIQM to PM to allow forbetter DCO frequency mapping. An Example of harmonic crosstalk scenariosmay be a band combination 2A-8A (1850-1910 MHz vs. 880-915 MHz). In thisscenario, a second harmonic of the band eight transmitter (2×915MHz=1830 MHz) is very close in frequency to the band two transmitter,which leads to a different cross talk behavior (and crosstalk mitigationmeasures) for polar or IQ architectures. Especially in polar operation,an instant frequency of the exact second harmonic may occur due tomodulation of the synthesizer signal. More critical band combinationsinclude Bd2-Bd20 (1850-1910 MHz vs. 832-862 MHz with second harmoniccrosstalk) and Bd1-Bd28 (1920-1980 MHz vs. 703-748 MHz with thirdharmonic crosstalk).

Although PM is preferred from a power perspective, if the demands ofusing two or more carriers at the same time, considering the harmonics,expected crosstalk, or tuning range suggest use of the DIQM, then thedevice may be switched to the DIQM to achieve the desired performance.

By way of example, the remote unit may be configured to transmit in afirst band using LTE 20 in PM. The base station then informs the remoteunit to prepare for dual band transmission. The remote unit, based onthe indication of preparing for dual band transmission, switches thetransmission of the first band to use the DIQM (and the other wayaround, i.e., for the second band). The system does not require that alltransmission bands use the same mode. Therefore, it is possible that,based on various criteria described herein, one band uses the PM andanother band uses DIQM. Examples of criteria may be used output power(for the higher power, polar has best efficiency), or location of thereceiving bands (in two carrier (2CA) upload (UL) there may only be oneRX band active, and IQ may give more or margin at the duplex distance),or IQ may be used near the frequency band edge of a DCO because itrequires no additional tuning range for modulation.

3) Contiguous Single-Carrier to Multiple-Carrier Transitions S640

When the remote unit receives an indication from the base station thatit is to switch from a single-carrier mode to a contiguousmultiple-carrier mode S640:MULTIPLE, the device may be switched from thePM to the DIQM S680, and vice versa (S640:SINGLE, S670). As noted above,this transition may occur on a band-by-band basis. This configuration issimilar to the determination of switching based on bandwidth, due to thefact that contiguous carriers may be considered functionally similar toincreasing bandwidth.

By way of example, LTE 20 consists of one-hundred resource blocks, thatis, one-hundred separate small frequency bands. For a channel bandwidthof 20 MHz, one-hundred numbered resource blocks of 200 kHz are providednext to each other. The base station indicates which of these numberedresource blocks should be utilized by the remote unit. If the resourceload involves blocks around the midrange, that is, blocks around numberfifty, then the system could determine that the PM is appropriate fortransmission. However, if the numbered resource blocks are in the cornerof the range (that is, blocks zero and ninety-nine), then there may be aproblem with utilizing PM, and the DIQM may be chosen.

Note that the number of resource blocks can change, and if the combinedbandwidth is within 20 MHz, then this is called “single carrier”, and ifit is above 20 MHz then it is called multiple carrier. For example,consider two contiguous carriers—in this case, one may count resourceblocks (RB) from one to two-hundred. If you are using just two RB, forexample, RB99 and RB101 there is only 600 kHz of bandwidth, but this isstill considered “multi-carrier” because it occupies two carriers (withone RB each). If using RB1 and RB99, this is still considered “singlecarrier” (carrier1 has RB1-100 and carrier2 has RB101-200).

Based on this there may be an additional criteria on which to switch.For example, the switching may occur based on the location of theresource blocks (i.e., their proximity to one another. The polar modemay be better when locations of the resource blocks are clustered in themiddle (e.g., RB49 and 50) and DIQM may be better when the resourceblocks are found at the edges (e.g., RB1 and RB100). Polar is better forclose RB combinations (power advantage, smaller bandwidth), but has adrawback at the edges (RB1 and RB100) due to a statistically high numberof zero crossings in the constellation diagram leading to high bandwidthrequirements.

4) Low EVM to High EVM Transitions S645

An error vector is a vector (distance) in the I-Q plane between an idealconstellation point and a point received by the receiver. The averageamplitude of the error vector, normalized to peak signal amplitude, isthe error vector magnitude (EVM) (also called receive constellationerror). EVM provides a comprehensive measure of radio receiver ortransmitter quality for use in digital communications, and the EVM maybe degraded by noise, distortion, spurious signals, and phase noise.

When the remote unit receives an indication from the base station thatis to switch from a low EVM requirement to a high EVM requirementS645:HIGH, based, for example, on quality-of-service (QoS) ormodulation-order requirements, the RF-DAC may be switched from the PM tothe DIQM S680, and vice versa (S645:LOW, S670), based on a presumptionthat better EVM may be obtained with digital IQ. The EVM trigger may bebased on a threshold EVM value, or it may be derived from, e.g., theorder of the modulation scheme derived below. High modulation schemesgenerally require high EVM, but there are also softer criteria likehigher coding gain (with the same modulation scheme) that require ahigher EVM. Thus, the modulation scheme and EVM requirement reflectseparate criteria. In an LTE environment, for example, it may bedesirable to utilize the PM when a lower order modulation scheme, suchas 64-QAM (quadrature amplitude modulation with 64 points (states) onthe constellation) is used, but then to switch to the DIQM when a higherorder modulation scheme, such as 256-QAM is used, due to the greaternoise susceptibility of the latter. The split between low- andhigh-order modulation schemes could be determined between any number ofpoints or states on the constellation.

5) LTE to 5G Transitions S650

When the remote unit receives an indication that is to switch from LTEto a 5G transmission S650:5G, the RF-DAC may be switched from the PM tothe DIQM S680, and vice versa (S650:LTE, S670). The switch to and from5G may represent a number of variables or factors to consider,including, but not limited to power, EVM, DCO bandwidth, duplexspecification, noise requirements, RF output power, RB constellationconfigurations, and other requirements, that warrant a change to thetransmit mode.

6) LTE to Wi-Fi Transitions S655

When the remote unit receives an indication from the base station toswitch from LTE to Wi-Fi S655:WI-FI, the device of the remote unit, ifit is operating in a PM, may be switched to operate in a DIQM S680, andvice versa (S655:LTE, S670). This switching may be performed independentof the signal bandwidth. Even if both Wi-Fi and LTE are at a particulardesignated frequency. Note that Wi-Fi 20 and LTE 20, even though theyspecify 20 MHz, may actually operate at different bandwidths (LTE 20operates around 15 MHz, whereas Wi-Fi 20 operates around 20 MHz).

7) Single to Multiple Transmitters at Same Frequency Transitions S660

The base station may switch from a single transmitter to multipletransmitters that operate at a same frequency S660:MULTIPLE, andtherefore, if it is operating in a PM, may be switched to operate in aDIQM S680, and vice versa (S660:SINGLE, S670). Although one possibleimplementation may be in a multiple input, multiple output (MIMO)operation, the concept is not so limited. The switching may occurwhether the multiple transmitters are directional (by providing anoutput signal at a same frequency with a phase shift between the two,creating a beamformed signal) or whether they utilize different codes ina code division multiple access (CDMA) channel access method.

In DIQM, the synthesizer is not modulated—it operates at a fixedfrequency, which provides an advantage in certain circumstances. Forexample, if it is desired to have a 2 GHz signal at the transmitter, fora single transmitter and using PM, the DCO is modulated at 4 GHz and thephase of the signal is directly modulated on the DCO. However, it is notpossible to add a second transmitter with an independent signal also at2 GHz using the same DCO, since the DCO operating at 4 GHz is modulatedwith the signal of the first transmitter (operation of two DCOs at thesame frequency on a chip is not possible, since the inductors wouldcouple). Therefore, the device may be switched to the DIQM since the DCOis not modulated and has a single frequency (the modulation is onlyadded in the RF-DAC). This permits a high number of transmitters to belocated on the same chip, which all use the same DCO.

The following table summarizes the modes of operation and thetransmission changes that may be used to trigger a change of a firstoperation mode to a second operation mode. By utilizing these operationmodes as described herein, devices may realize an improvement in a powerkey performance indicator and reduce the chip area of an RF product.Furthermore, this design may enable new features at higher bandwidths.

TABLE 1 Summary of Switching/Operating Modes Digital IQ Mode (DIQM)Polar Mode (PM) Vector-modulated RF Polar-modulated RF Output SignalOutput Signal Mode Characteristics Poorer power Better power consumptionconsumption Operable at higher Inoperable at higher frequenciesfrequencies 1) Low-bandwidth to High- Operate in DIQM when over Operatein PM when below Bandwidth Transitions a bandwidth threshold a bandwidththreshold. 2) Non-Contiguous Single- Operate in DIQM for Operate in PMfor single Carrier to Dual-Carrier- multiple carrier when risk ofcarrier for better DCO Multiple-Carrier Transitions harmonic crosstalk(change frequency mapping in DCO frequency) 3) Contiguous Single-Operate in DIQM when Operate in PM when using Carrier toMultiple-Carrier multiple carriers exceed a single carrier. Transitionsbandwidth threshold; Operate in PM when blocks Operate in DIQM when arein the middle of a range blocks are in the corner of a range 4) Low EVMto High EVM Operate in DIQM when Operate in PM when there is Transitionsthere is a high EVM a low EVM requirement requirement (e.g., LTE for(e.g., LTE for 64-QAM) 256-QAM) 5) LTE to 5G Transitions Operate in DIQMwhen Operate in PM when using using 5G communications LTE communications6) LTE to Wi-Fi Transitions Operate in DIQM when Operate in PM whenusing using Wi-Fi LTE communications communications 7) Single toMultiple Multiple transmitters at Single transmitter operatesTransmitters at Same same frequency operate in in PM Frequency DIQM

FIG. 7 is a block diagram illustrating a machine that may be a computeror communications device on which various processes described herein maybe performed. The machine (e.g., computer system) 700 may include ahardware processor 702 (e.g., a central processing unit (CPU), which maybe an implementation of the processor 322 discussed above, a graphicsprocessing unit (GPU), a hardware processor core, or any combinationthereof), a main memory 704 and a static memory 706, which may be animplementation of the memory 324 discussed above, some or all of whichmay communicate with each other via an interlink (e.g., bus) 708. Themachine 700 may further include a display unit 710, an alphanumericinput device 712 (e.g., a keyboard), and a user interface (UI)navigation device 714 (e.g., a mouse). In an example described herein,the display unit 710, input device 712 and UI navigation device 714 maybe a touch screen display. The machine 700 may additionally include astorage device (e.g., drive unit) 716, a signal generation device 718(e.g., a speaker), a network interface device 720, and one or moresensors 721, such as a global positioning system (GPS) sensor, compass,accelerometer, or other sensor. The machine 700 may include an outputcontroller 728, such as a serial (e.g., universal serial bus (USB)),parallel, or other wired or wireless (e.g., infrared (IR), near fieldcommunication (NFC), etc.) controller connection to communicate orcontrol one or more peripheral devices (e.g., a printer, card reader,etc.).

The storage device 716 may include a machine readable medium 722 onwhich is stored one or more sets of data structures or instructions 724(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 724 may alsoreside, completely or at least partially, within the main memory 704,within static memory 706, or within the hardware processor 702 duringexecution thereof by the machine 700. In an example, one or anycombination of the hardware processor 702, the main memory 704, thestatic memory 706, or the storage device 716 may constitute machinereadable media.

While the machine readable medium 722 is illustrated as a single medium,the term “machine readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 724.

The term “machine readable medium” may include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe machine 700 and that cause the machine 700 to perform any one ormore of the techniques of the present disclosure, or that is capable ofstoring, encoding or carrying data structures used by or associated withsuch instructions. Non-limiting machine readable medium examples mayinclude solid-state memories, and optical and magnetic media. Specificexamples of machine readable media may include: non-volatile memory,such as semiconductor memory devices (e.g., Electrically ProgrammableRead-Only Memory (EPROM), Electrically Erasable Programmable Read-OnlyMemory (EEPROM)) and flash memory devices; magnetic disks, such asinternal hard disks and removable disks; magneto-optical disks; RandomAccess Memory (RAM); Solid State Drives (SSD); and CD-ROM and DVD-ROMdisks. In some examples, machine readable media may includenon-transitory machine readable media. In some examples, machinereadable media may include machine readable media that is not atransitory propagating signal.

The instructions 724 may further be transmitted or received over thecommunications network 105 using a transmission medium via the networkinterface device 720. The term “transmission medium” is defined hereinto include any medium that is capable of storing, encoding, or carryinginstructions for execution by the machine, and includes digital oranalog communications signals or other medium to facilitatecommunication of such software.

The machine 700 may communicate with one or more other machines 700utilizing any one of a number of transfer protocols (e.g., frame relay,internet protocol (IP), transmission control protocol (TCP), userdatagram protocol (UDP), hypertext transfer protocol (HTTP), etc.).Example communication networks may include a local area network (LAN), awide area network (WAN), a packet data network (e.g., the Internet),mobile telephone networks (e.g., cellular networks), Plain Old Telephone(POTS) networks, and wireless data networks (e.g., Institute ofElectrical and Electronics Engineers (IEEE) 802.11 family of standardsknown as Wi-Fi®, WiGig®, IEEE 802.16 family of standards known asWiMax®), IEEE 802.15.4 family of standards, a Long Term Evolution (LTE)family of standards, a Universal Mobile Telecommunications System (UMTS)family of standards, peer-to-peer (P2P) networks, virtual privatenetworks (VPN), or any other way of transferring data between machines700. In an example, the network interface device 720 may include one ormore physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one ormore antennas to connect to the communications network 726.

In an example, the network interface device 720 may include a pluralityof antennas to wirelessly communicate using at least one of single-inputmultiple-output (SIMO), multiple-input multiple-output (MIMO), ormultiple-input single-output (MISO) techniques. In some examples, thenetwork interface device 720 may wirelessly communicate using MultipleUser MIMO techniques.

A wide variety of computing devices may constitute a machine 700, asdescribed herein. The following list includes a variety of devices thatmay fit the definition of a machine 700: a personal data assistant(PDA), a cellular telephone, including a smartphone, a tablet computingdevice, a laptop computer, a desktop computer, a workstation, a servercomputer, a mainframe computer, and the like.

For the purposes of promoting an understanding of the principles of thisdisclosure, reference has been made to the various configurationsillustrated in the drawings, and specific language has been used todescribe these configurations. However, no limitation of the scope ofthe inventive subject matter is intended by this specific language, andthe inventive subject matter should be construed to encompass allembodiments and configurations that would normally occur to one ofordinary skill in the art. The configurations herein may be described interms of functional block components and various processing steps. Suchfunctional blocks may be realized by any number of components thatperform the specified functions. The particular implementations shownand described herein are illustrative examples and are not intended tootherwise limit the scope of the inventive subject matter in any way.The connecting lines, or connectors shown in the various figurespresented may, in some instances, be intended to represent examplefunctional relationships and/or physical or logical couplings betweenthe various elements. However, many alternative or additional functionalrelationships, physical connections or logical connections may bepresent in a practical device. Moreover, no item or component isessential unless the element is specifically described as “essential” or“critical”. Numerous modifications and adaptations will be readilyapparent to those skilled in this art.

EXAMPLES

Example 1 is a transmitter device switchably operable in a digital IQmode (DIQM) of operation and a polar mode (PM) of operation, comprising:a switch logic processor that determines an attribute of operation ofthe transmitter device; a switch that is connected to the switch logicprocessor and that is to switch operation of the device between the DIQMof operation and the PM of operation; when a first condition of theattribute is met, then the switch is to switch to or remain in the PM;and when a second condition of the attribute is met, then the switch isto switch to or remain in the DIQM.

In Example 2, the subject matter of Example 1 optionally includeswherein: the attribute is a modulation bandwidth to be used during atransmission time slot; the first condition is that the modulationbandwidth is less than or equal to a predefined bandwidth threshold(BT); and the second condition is that the modulation bandwidth isgreater than the predefined BT.

In Example 3, the subject matter of any one or more of Examples 1-2optionally include wherein: the attribute is whether a transmission isto be a non-contiguous single-carrier transmission or a non-contiguousmultiple-carrier transmission to be used during a transmission timeperiod; the first condition is that the transmission is to be anon-contiguous single-carrier transmission; and the second condition isthat the transmission is to be a non-contiguous multiple-carriertransmission.

In Example 4, the subject matter of any one or more of Examples 1-3optionally include wherein: the attribute is whether a transmission isto be a contiguous single-carrier transmission or a contiguousmultiple-carrier transmission to be used during a transmission timeperiod; the first condition is that the transmission is to be acontiguous single-carrier transmission; and the second condition is thatthe transmission is to be a contiguous multiple-carrier transmission.

In Example 5, the subject matter of any one or more of Examples 1-4optionally include wherein: the attribute is whether a low or high EVMmode transmission is to be used during a transmission time period; thefirst condition is that the transmission is to be a low EVMtransmission; and the second condition is that the transmission is to bea high EVM transmission.

In Example 6, the subject matter of Example 5 optionally includeswherein: the low EVM transmission utilizes a 64-QAM or lower ordermodulation scheme; and the high EVM transmission utilizes a 256-QAM orhigher order modulation scheme.

In Example 7, the subject matter of any one or more of Examples 1-6optionally include wherein: the attribute is whether an LTE or a 5G modetransmission is to be used during a transmission time period; the firstcondition is that the transmission is to be an LTE transmission; and thesecond condition is that the transmission is to be a 5G transmission.

In Example 8, the subject matter of any one or more of Examples 1-7optionally include wherein: the attribute is whether an LTE or a Wi-Fimode transmission is to be used during a transmission time period; thefirst condition is that the transmission is to be an LTE transmission;and the second condition is that the transmission is to be a Wi-Fitransmission.

In Example 9, the subject matter of any one or more of Examples 1-8optionally include wherein: the attribute is whether a single ormultiple transmitters will be used at a same frequency during atransmission time period; the first condition is that the transmissionis to use a single transmitter; and the second condition is that thetransmission is to use multiple transmitters at a same frequency.

In Example 10, the subject matter of any one or more of Examples 1-9optionally include wherein the time period is a time slot.

In Example 11, the subject matter of any one or more of Examples 1-10optionally include MHz.

In Example 12, the subject matter of any one or more of Examples 1-11optionally include wherein, in a dual band mode of operation, a firstband uses PM and a second band uses DIQM.

Example 13 is a method for operating a transmitter device that isswitchably operable between a digital IQ mode (DIQM) of operation and apolar mode (PM) of operation, the method comprising: determining, with aswitch, an attribute of operation of the transmitter device; when afirst condition of the attribute is met, switching to or remaining inthe PM; and when a second condition of the attribute is met, switchingto or remaining in the DIQM.

In Example 14, the subject matter of Example 13 optionally includeswherein: the attribute is a modulation bandwidth to be used during atransmission time slot; the first condition is that the modulationbandwidth is less than or equal to a predefined bandwidth threshold(BT); and the second condition is that the modulation bandwidth isgreater than the predefined BT.

In Example 15, the subject matter of any one or more of Examples 13-14optionally include wherein: the attribute is whether a transmission isto be a non-contiguous single-carrier transmission or a non-contiguousmultiple-carrier transmission to be used during a transmission timeperiod; the first condition is that the transmission is to be anon-contiguous single-carrier transmission; and the second condition isthat the transmission is to be a non-contiguous multiple-carriertransmission.

In Example 16, the subject matter of any one or more of Examples 13-15optionally include wherein: the attribute is whether a transmission isto be a contiguous single-carrier transmission or a contiguousmultiple-carrier transmission to be used during a transmission timeperiod; the first condition is that the transmission is to be acontiguous single-carrier transmission; and the second condition is thatthe transmission is to be a contiguous multiple-carrier transmission.

In Example 17, the subject matter of any one or more of Examples 13-16optionally include wherein: the attribute is whether a low or high EVMmode transmission is to be used during a transmission time period; thefirst condition is that the transmission is to be a low EVMtransmission; and the second condition is that the transmission is to bea high EVM transmission.

In Example 18, the subject matter of Example 17 optionally includeswherein: the low EVM transmission utilizes a 64-QMM or lower ordermodulation scheme; and the high EVM transmission utilizes a 256-QMM orhigher order modulation scheme.

In Example 19, the subject matter of any one or more of Examples 13-18optionally include wherein: the attribute is whether an LTE or a 5G modetransmission is to be used during a transmission time period; the firstcondition is that the transmission is to be an LTE transmission; and thesecond condition is that the transmission is to be a 5G transmission.

In Example 20, the subject matter of any one or more of Examples 13-19optionally include wherein: the attribute is whether an LTE or a Wi-Fimode transmission is to be used during a transmission time period; thefirst condition is that the transmission is to be an LTE transmission;and the second condition is that the transmission is to be a Wi-Fitransmission.

In Example 21, the subject matter of any one or more of Examples 13-20optionally include wherein: the attribute is whether a single ormultiple transmitters will be used at a same frequency during atransmission time period; the first condition is that the transmissionis to use a single transmitter; and the second condition is that thetransmission is to use multiple transmitters at a same frequency.

In Example 22, the subject matter of any one or more of Examples 13-21optionally include wherein the time period is a time slot.

In Example 23, the subject matter of any one or more of Examples 13-22optionally include MHz.

In Example 24, the subject matter of any one or more of Examples 13-23optionally include wherein, in a dual band mode of operation, a firstband uses PM and a second band uses DIQM.

Example 25 is a computer program product comprising one or more tangiblecomputer readable non-transitory storage media comprisingcomputer-executable instructions operable to, when executed byprocessing circuitry of a device, configure the device to: operate atransmitter device that is switchably operable between a digital IQ mode(DIQM) of operation and a polar mode (PM) of operation, to: determine,with a switch, an attribute of operation of the transmitter device; whena first condition of the attribute is met, switch to or remain in thePM; and when a second condition of the attribute is met, switch to orremain in the DIQM.

In Example 26, the subject matter of Example 25 optionally includeswherein: the attribute is a modulation bandwidth to be used during atransmission time slot; the first condition is that the modulationbandwidth is less than or equal to a predefined bandwidth threshold(BT); and the second condition is that the modulation bandwidth isgreater than the predefined BT.

Example 27 is a computer program product comprising one or more computerreadable storage media comprising computer-executable instructionsoperable to, when executed by processing circuitry of a device,configure the device to perform any of the methods of Examples 13-24.

Example 28 is a system comprising means to perform any of the methods ofExamples 13-24.

Example 29 is an apparatus for operating a transmitter device that isswitchably operable between a digital IQ mode (DIQM) of operation and apolar mode (PM) of operation, comprising: means for determining, with aswitch logic processor, an attribute of operation of the transmitterdevice; means for switching operation of the device between the DIQM ofoperation and the PM of operation; means for, when a first condition ofthe attribute is met, switching to or remaining in the PM; and meansfor, when a second condition of the attribute is met, switching to orremaining in the DIQM.

In Example 30, the subject matter of Example 29 optionally includeswherein: the attribute is a modulation bandwidth to be used during atransmission time slot; the first condition is that the modulationbandwidth is less than or equal to a predefined bandwidth threshold(BT); and the second condition is that the modulation bandwidth isgreater than the predefined BT.

In Example 31, the subject matter of any one or more of Examples 29-30optionally include wherein: the attribute is whether a transmission isto be a non-contiguous single-carrier transmission or a non-contiguousmultiple-carrier transmission to be used during a transmission timeperiod; the first condition is that the transmission is to be anon-contiguous single-carrier transmission; and the second condition isthat the transmission is to be a non-contiguous multiple-carriertransmission.

In Example 32, the subject matter of any one or more of Examples 29-31optionally include wherein: the attribute is whether a transmission isto be a contiguous single-carrier transmission or a contiguousmultiple-carrier transmission to be used during a transmission timeperiod; the first condition is that the transmission is to be acontiguous single-carrier transmission; and the second condition is thatthe transmission is to be a contiguous multiple-carrier transmission.

In Example 33, the subject matter of any one or more of Examples 29-32optionally include wherein: the attribute is whether a low or high EVMmode transmission is to be used during a transmission time period; thefirst condition is that the transmission is to be a low EVMtransmission; and the second condition is that the transmission is to bea high EVM transmission.

In Example 34, the subject matter of Example 33 optionally includeswherein: the low EVM transmission utilizes a 64-QMM or lower ordermodulation scheme; and the high EVM transmission utilizes a 256-QMM orhigher order modulation scheme.

In Example 35, the subject matter of any one or more of Examples 29-34optionally include wherein: the attribute is whether an LTE or a 5G modetransmission is to be used during a transmission time period; the firstcondition is that the transmission is to be an LTE transmission; and thesecond condition is that the transmission is to be a 5G transmission.

In Example 36, the subject matter of any one or more of Examples 29-35optionally include wherein: the attribute is whether an LTE or a Wi-Fimode transmission is to be used during a transmission time period; thefirst condition is that the transmission is to be an LTE transmission;and the second condition is that the transmission is to be a Wi-Fitransmission.

In Example 37, the subject matter of any one or more of Examples 29-36optionally include wherein: the attribute is whether a single ormultiple transmitters will be used at a same frequency during atransmission time period; the first condition is that the transmissionis to use a single transmitter; and the second condition is that thetransmission is to use multiple transmitters at a same frequency.

In Example 38, the subject matter of any one or more of Examples 29-37optionally include wherein the time period is a time slot.

In Example 39, the subject matter of any one or more of Examples 29-38optionally include MHz.

In Example 40, the subject matter of any one or more of Examples 29-39optionally include wherein, in a dual band mode of operation, a firstband uses PM and a second band uses DIQM.

1. A transmitter device switchably operable in a digital IQ mode (DIQM)of operation and a polar mode (PM) of operation, comprising: a switchlogic processor to determine an attribute of operation of thetransmitter device; and a switch connected to the switch logic processorand that is to switch operation of the transmitter device between theDIQM of operation and the PM of operation, wherein when a firstcondition of the attribute is met, then the switch is to switch to orremain in the PM, and when a second condition of the attribute is met,then the switch is to switch to or remain in the DIQM; wherein: theattribute is whether a low or high error vector magnitude (EVM) modetransmission is to be used during a transmission time period; the firstcondition is that the transmission is to be a low EVM transmission; andthe second condition is that the transmission is to be a high EVMtransmission. 2-5. (canceled)
 6. The transmitter device of claim 1,wherein: the low EVM transmission utilizes a 64-quadrature amplitudemodulation (QAM) or lower order modulation scheme; and the high EVMtransmission utilizes a 256-QAM or higher order modulation scheme. 7-11.(canceled)
 12. A transmitter device switchably operable in a digital IQmode (DIQM) of operation and a polar mode (PM) of operation, comprising:a switch logic processor to determine an attribute of operation of thetransmitter device; and a switch connected to the switch logic processorand that is to switch operation of the transmitter device between theDIQM of operation and the PM of operation, wherein when a firstcondition of the attribute is met, then the switch is to switch to orremain in the PM, and when a second condition of the attribute is met,then the switch is to switch to or remain in the DIQM; wherein, in adual band mode of operation, a first band uses PM and a second band usesDIQM.
 13. A method for operating a transmitter device that is switchablyoperable between a digital IQ mode (DIQM) of operation and a polar mode(PM) of operation, the method comprising: determining with a switchlogic processor, an attribute of operation of the transmitter device;when a first condition of the attribute is met, switching to orremaining in the PM; and when a second condition of the attribute ismet, switching to or remaining in the DIQM; wherein: the attribute iswhether a low or high error vector magnitude (EVM) mode transmission isto be used during a transmission time period; the first condition isthat the transmission is to be a low EVM transmission; and the secondcondition is that the transmission is to be a high EVM transmission.14-17. (canceled)
 18. The method of claim 13, wherein: the low EVMtransmission utilizes a 64-Quadrature amplitude modulation (QAM) orlower order modulation scheme; and the high EVM transmission utilizes a256-QAM or higher order modulation scheme. 19-22. (canceled)
 23. Amethod for operating a transmitter device that is switchably operablebetween a digital IQ mode (DIQM) of operation and a polar mode (PM) ofoperation, the method comprising: determining with a switch logicprocessor, an attribute of operation of the transmitter device; when afirst condition of the attribute is met, switching to or remaining inthe PM; and when a second condition of the attribute is met, switchingto or remaining in the DIQM; wherein, in a dual band mode of operation,a first band uses PM and a second band uses DIQM.
 24. A computer programproduct comprising one or more tangible computer readable non-transitorystorage media comprising computer-executable instructions operable to,when executed by processing circuitry of a device, configure the deviceto: operate a transmitter device that is switchably operable between adigital IQ mode (DIQM) of operation and a polar mode (PM) of operation,to: determine, with a switch logic processor, an attribute of operationof the transmitter device; when a first condition of the attribute ismet, switch to or remain in the PM; and when a second condition of theattribute is met, switch to or remain in the DIQM; wherein: theattribute is whether a low or high error vector magnitude (EVM) modetransmission is to be used during a transmission time period; the firstcondition is that the transmission is to be a low EVM transmission; andthe second condition is that the transmission is to be a high EVMtransmission.
 25. (canceled)